Recently, through silicon via (TSV) is used in a semiconductor device as an electrode that penetrates perpendicularly through a semiconductor substrate on which various electronic elements are provided. By electrically connecting a plurality of semiconductor chips using this TSV, the plurality of semiconductor chips are mounted with high density, and high speed data communication, and the like, is enabled.
The TSV is formed by a via last/backside via TSV process, for example. In detail, after forming active elements on a semiconductor substrate, such as memories, wiring layers that connect those elements, and surface side electrodes for connecting to the TSV formed on subsequent processes, the semiconductor substrate is adhered onto a support substrate, such as glass, using adhesive or the like. The semiconductor substrate is attached to the support substrate so that the surface of the semiconductor substrate, on which the active elements, the wire layers and the surface side electrodes are present, faces the support substrate. Thereafter, by grinding the back surface of the semiconductor substrate, a film thickness of several hundreds of μm is thinned down to several tens of μm, for example. Next, the TSV is formed using a method, such as lithography, dry etching, plating, chemical mechanical planarization (CMP), and the like, and a TSV hole that penetrates the semiconductor substrate from the back surface side of the semiconductor substrate is formed. For the TSV hole, a barrier metal is formed by spattering, and then, a metal film, such as a copper film, is embedded by plating. Moreover, by removing an excess metal film using CMP, the TSV is formed. Then, a back side electrode is formed on a bump by using a method, such as sputtering, lithography, plating, wet etching, and the like.
By forming a plurality of semiconductor chips by separating (dividing) such a semiconductor substrate, and by stacking the semiconductor chips, a stacked module is formed. In the stacked module, devices included in each of the stacked semiconductor chips are electrically connected to each other by using the TSV and bumps.